Recent studies in our laboratories have indicated that the aromatic ring or hallucinogenic phenethylamine derivatives corresponds structurally to the pyrrole portion of the indole nucleus in LSD and hallucinogenic tryptamines. Further, this implies that the ability of hallucinogens to stimulate serotonin receptors may lie in functional similarity between the corresponding aromatic regions of the molecules. The objectives of this study are to prepare and pharmacologically evaluate substituted 1,2-dihydro-2-naphthylamines as rigid analogues intermediate in structure between phenethylamines and the indole type hallucinogens. Theoretical calculations, and quantitative structure activity relationship studies will be developed to define parameters which are important for hallucinogenic or serotonin like activity in the proposed series. The studies will test the hypothesis that the aromatic phenethylamine ring functionally corresponds to the pyrrole region in indole hallucinogens. The long range goal is to gain a clearer understanding of the mechanism of action for hallucinogens, and to define steric and electronic requirements for hallucinogenic activity. Especially, in view of the probable involvement of serotoinergic pathways in this action, we hope to be able to define the requirements for activity at serotonin receptors.